1. Field of the Invention
This invention relates to synthetically derived high density liquid hydrocarbon fuels.
2. Description of the Prior Art
High density liquid hydrocarbon fuels are characterized in having a net volumetric heat of combustion in excess of about 140,000 BTU per gallon. A high density or high energy fuel is essentially required for fueling turbojet and ramjet propelled limited volume missile systems. Beyond the need for a high energy content in order to maximize range performance of the missile, there are other requirements in the forefront depending, in the main, on the manner in which the missile is to be deployed. For instance, in the air-borne deployment of a missile where the latter is carried exteriorly of the aircraft, the fuel must exhibit the combination of a very low freeze point, high volatility and be reasonably fluid at the low temperatures encountered.
A high density fuel of the foregoing type does not occur in nature rather must be chemically synthesized. Essentially all of the current generation of such fuels commonly feature a norbornane moiety having an additional cyclic hydrocarbon appendage. A noteworthy fuel of the foregoing type is represented by the exo-stereo isomer of tetrahydrodicyclopentadiene which in commerce is generally referred to as JP-10. The latter is prepared by first hydrogenating dicyclopentadiene yielding the solid endo-isomer of the hydrogenated derivative. The endo structure is then isomerized in the presence of a catalyst to produce the exo-isomer almost quantitatively in a relatively pure form. Since JP-10 is derived from abundantly available raw materials coupled with the fact that the isomerization procedure is highly developed, such are the main factors why the product is regarded as a prime fuel.
Neat JP-10, however, fails as a universal fuel because of its flash point. The flash point of JP-10 is too low, although only marginally so, for ship or submarine launching operations; whereas, it is considerably higher than that required in air-borne deployment of the missile system. The object of this invention, accordingly, is that of modifying JP-10 in a manner whereby the flash point is substantially reduced without significantly diluting the high heat content associated with the fuel itself.